1. Field of the Invention
This invention relates to controlling the environment about an underwater pile or other structure. More particularly, the invention relates to a process for controlling the environment about an underwater or submerged pile and applying various preservative techniques to reduce deterioration of the pile due to wave action, tides, corrosion, insects, marine animals and so forth.
2. Description of Related Art Including Information Disclosed under 37 C.F.R. Sections 1.97-1.99
Piers, off-shore oil platforms and the like are customarily anchored and supported by steel piles that are driven deep into the sea floor. These piles are typically steel pipes that may range in diameter from a few inches to a several feet. They may be very long.
In some applications wooden piles are used. Wooden piles are typically treated with a preservative to extend their lives, but they also suffer deterioration from rot, boring animals and the like, which normally extends from the top of the pile to the mud line. Sheet piles are also frequently used, most commonly to prevent erosion of a shore line.
These three forms of piles, that is, steel piles, wooden piles, and sheet piles, as well as other underwater structures will be referred to collectively as "piles" herein. The piles corrode or otherwise deteriorate and attract destructive marine life, such as barnacles. The portion of the pile that is sunk into the sea floor typically does not corrode much because there is very little oxygen available there. Further, as the water becomes deeper, there is less oxygen in it and less corrosion or other deterioration.
The portion of the pile that is subjected to wave action and tides, that is, the portion relatively close to the surface, suffers from significant corrosion or other deterioration, which significantly shortens the life of such structures. This splash zone usually does not exceed forty feet, even in areas such as the North Sea. Accordingly, forty feet is frequently the longest portion of a pile that would be protected. Protecting the splash zone of piles is particularly important because the repeated wetting and drying of the pile accelerates corrosion and other deterioration, especially in salt water.
In the case of wooden piles, boring marine animals and other deterioration typically affects the pile throughout the length from the top of the pile to the mud line and this entire length should be treated. Further, wooden piles should be repaired and strengthened, especially when significant damage has been done to them.
Efforts to address these problems have led to a number of proposed solutions in the related art. Many of these efforts to prevent or reduce that corrosion are largely ineffective over the long term. They include, for example, wrapping the piles with gauze-like material saturated with heavy petroleum or grease, which can wash away, leaving the pile unprotected and polluting the environment. Other coatings are applied underwater after the pile has been installed. Some of these proposed solutions have led to patented inventions. The related art known to the inventor is discussed below.
U.S. Pat. No. 4,993,876, issued to Snow et al., discloses a "Method and Apparatus for Protective Encapsulation of Structural Members" which involves applying a jacket to the desired portion of a pile and injecting a two part reactive polymer mixture into the jacket. A different color can be included in each polymer component to form a third color when the two components mix, allowing visual monitoring of the degree of mixing and the distribution of the mixture when a transparent or translucent jacket is used. The components are mixed outside of the jacket. The jacket is sealed at the bottom and the polymer (such as epoxy) displaces the water from inside the jacket as it is injected. Prior to installation of the jacket, the pile must be cleaned twice by hand and a biological inhibitor solution may be injected into the jacket prior to grouting. No details are disclosed regarding the seal at the bottom of the jacket. Standing water in the installed jacket is not removed except when displaced by the polymer mixture, which includes three principal components in the preferred embodiment and apparently does not expand as it cures.
U.S. Pat. No. 4,983,072, issued to Bell, Jr., discloses a "Method of Protecting Submerged Piling" in which a pile is surrounded by a flexible sheet of plastic that is resistant to ultraviolet radiation. The sheet is porous. It forms a space around the pile. That space is filled with a filler material, such as sand and silt, which, according the patent, keeps marine pests from boring into the pile. Bell, Jr. U.S. Pat. No. '072 does not disclose the manner of attachment of the sheet to the pile.
U.S. Pat. No. 4,764,054, issued to Sutton, discloses a "Piling-Jacket System and Method" in which a split jacket is held in place by a steel band at each end. A zipper is used to close the lengthwise split in the jacket. The steel bands are seated in notches or grooves cut into the pile. These grooves weaken the pile. A rigid access tube is inserted through an open port in the jacket for injecting grout. It appears that concrete is the grout of choice. Standing water within the jacket is not removed prior to filling the space with grout, but is merely displaced by the incoming grout, which must be injected in two stages, with some curing allowed prior to the second injection to prevent leakage at the bottom of the jacket. Waiting for some grout to cure before complete the job increases both the labor and capital costs.
U.S. Pat. No. 4,697,957, issued to Hellmers, discloses a "Marine Pile Protective System" in which a split tube of extruded hexeneethylene copolymer is slipped around a pile and the split edges are snapped together. The seam is sealed with a foam polyurethane strip, as is the bottom of the jacket. The jacket can be drawn tightly against the pile by nylon webbing and is held in its final position by aluminum alloy nails. The jacket provides a water and air tight seal around the pile, excluding oxygen from the pile. There is no filler material within the jacket.
U.S. Pat. No. 4,306,821, issued to Moore, discloses a "Method and Apparatus for Restoring Piling" in which an outer form is attached to a portion of a damaged piling. A filler is placed into the space between the form and the piling. The form is secured to the piling with bands and a space is maintained between the form and the piling by spacers. The filler, preferably epoxy, can be introduced through a filler tube in the lower portion or a second filler tube at the top of the form, the latter of which can be progressively withdrawn as the filler is injected. The method can be used on either wet or dry portions of the piling. No effort is made to dry the piling prior to injection of the filler.
U.S. Pat. No. 3,736,759, issued to Bloese, discloses a "Pile Covering" in which a sheath is secured to the pile and an expandable filler material is expanded in place between the jacket and the pile to form a closed-cell filler. To develop greater adhesion between the foam and the jacket, the jacket may include friction ribs. The method may also include cleaning the pile, attaching the sheath, which is sealed by a collar below the water line, pumping out the standing water and drying the prior to injecting the filler. There is no indication of how these functions are accomplished.
These related art efforts to solve the problems of corrosion and other deterioration, however, suffer from serious shortcomings. These methods are difficult and expensive to use. Moreover, they provide only temporary and incomplete solutions to the problems of corrosion and other deterioration, often due to poor adhesion to a pile by any protective material. Many of the coatings fracture when vessels bump into them during berthing, allowing the water to come into contact with the water again. In this case, the coating may appear to protect the pile when it does not.
In another shortcoming, for example, they leave in place any contaminating materials already on the pile. Further, the jacket is left in place on the pile and it cannot be used again, but it does little to increase protection of the pile. There is no provision in the related art discussed herein for recovering any excess products or waste products, which may be toxic, that may be generated during treatment of a pile, increasing the threat to our marine environments.
The sheaths or jackets of these related art references are open at the top, restricting their use to structures that extend above the water line and requiring applications in which the top of the sheath is above the water line. Moreover, the related art discussed herein does not disclose or suggest any apparatus or process for creating a controlled, sealed environment about a portion of a submerged pile. Further, there is no disclosure of a system that can tolerate high pressures that can be necessary to force a coating into cracks and other surface defects of a pile.
Accordingly, there is a need for an apparatus and a process for creating a controlled environment about a portion of a pile to be treated and protected. Once a controlled environment is achieved, the space in that environment can be dried, then treated with any desired treatment to prevent further deterioration of the pile, to provide protection from future environmental hazards, to provide protection from impacts, and even to rebuild the structural integrity of the piles. In addition, important contributions to the environment can be made by recovering any excess chemical products or waste products generated during treatment of the piles. Fundamentally, a need exists for a means for creating a controlled, sealed environment about an underwater structure, such as a pile, and treating and repairing that structure, in order to extend the life of the structure at a substantial savings over replacing it.